Expands the `debounce` rule configuration to accept `'blur'`. When this option
is provided, the rule will delay model synchronization until the field loses
focus (is touched). This introduces a debouncer that defers resolution
until the framework automatically aborts pending debounces upon touch events.
(cherry picked from commit c767d678cf)
Remove `setControlValue()` from `FieldState` and convert `controlValue` to a
`WritableSignal` whose setter implements the debounced syncing behavior
of `setControlValue()`.
Removes the abort event listener once the debounce timeout completes.
This avoids lingering listeners, prevents potential memory leaks, and ensures
the abort logic runs at most once.
Add an `AbortSignal` parameter to `Debouncer`. Implementations may
choose to accept this parameter to be informed when a debounced
operation is aborted. This may be useful for canceling pending timers or
avoiding unnecessary work.
The `debounce()` rule allows developers to control when changes to a
form control are synchronized to the form model.
This feature necessitated some changes to `FieldState`:
* `controlValue` is a new signal property that represents the current
value of a form field as it appears in its corresponding control.
* `value` conceptually remains unchanged; however, its value may lag
behind that of `controlValue` if a `debounce()` rule is applied.
The `debounce()` rule essentially manages when changes to `controlValue` are
synchronized to `value`. The intent is that an expensive or slow
validation rule can react to the debounced `value`, rather than a more
frequently changing `controlValue`.
Directly updating `value` immediately updates `controlValue`, and cancels any
pending debounced updates.
When multiple `debounce()` rules are applied to the same field, the last
currently active rule is used to debounce an update. These rules are
applied to child fields as well, unless they override them with their
own rule.
